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遗留 Ruby on Rails 2.3 项目在这里。收到以下错误：

You have a nil object when you didn't expect it!
You might have expected an instance of ActiveRecord::Base.
The error occurred while evaluating nil.[]

提取的源代码（在 #122 行附近）：

119: <%= link_to 'Printable', { :action => 'print', :id => @incident.id }, { :target => '_blank', :class => "button" } %>
120: <% if isviewable?(@incident) %>
121: 
122:   <%= link_to "Pictures (#{@incident.pictures.count})", incident_pictures_path(@incident), :class => "button" %>
123:   <%= link_to "Suspects (#{@incident.suspects.count})", incident_suspects_path(@incident), :class => "button" %>
124:   <%= link_to "Notes (#{@incident.notes.count})", incident_notes_path(@incident), :class => "button"%>
125:   <%= link_to "Cars (#{@incident.cars.count})", incident_cars_path(@incident), :class => "button" %>

有什么想法吗？谢谢。

编辑：删除第 122 行修复了异常，但如果该记录有，我可能需要显示一张图片，所以我不能只删除该功能。

编辑2：应用程序跟踪下的异常页面中也有这一行：

/usr/local/rvm/gems/ruby-1.8.7-p371/gems/paperclip-2.3.0/lib/paperclip.rb:303:in `validates_attachment_content_type'

我的回形针插件可能有错误吗？

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2 回答 2

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119: <%= link_to 'Printable', { :action => 'print', :id => @incident.id }, { :target => '_blank', :class => "button" } %>
    <% if @incident.present?%>       #### you need to check for null object. ######
120: <% if isviewable?(@incident) %>
121:
122:   <%= link_to "Pictures (#{@incident.pictures.count})", incident_pictures_path(@incident), :class => "button" %>
123:   <%= link_to "Suspects (#{@incident.suspects.count})", incident_suspects_path(@incident), :class => "button" %>
124:   <%= link_to "Notes (#{@incident.notes.count})", incident_notes_path(@incident), :class => "button"%>
125:   <%= link_to "Cars (#{@incident.cars.count})", incident_cars_path(@incident), :class => "button" %>

您需要检查空对象，然后希望它可以正常工作。

于 2013-05-14T14:58:25.827 回答
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尝试在控制器中使用 .find_by_id 而不是 .find。然后，您可以在继续之前检查结果（@incident.nil？）。

编辑：

如何@incident.pictures?检查是否有？

于 2013-05-14T14:59:01.693 回答